Comparison of mass-weighted average LOS velocity 〈υ_LOS〉 of the model cloud and the mean radial velocity 〈υ〉 from ideal observations or from synthetic ngVLA observations. Frames show (a) true column density, (b) 〈υ〉 in ideal C¹⁸O observations, (c) 〈υ〉 in ideal N₂H⁺ observations, (d) 〈υ_LOS〉 convolved to 0.55″ resolution, (e) 〈υ〉 in synthetic ngVLA C¹⁸O observations, and (f) 〈υ〉 in synthetic ngVLA N₂H⁺ observations. The contour is drawn at column density N(H₂) = 5 × 10²² cm⁻², and regions of lower column density are masked in frames e and f.